This application relates to a method for the isolation of biosynthesis genes for antibiotics and other bioactive molecules from complex natural sources such as humus, soil and lichens.
Antibiotics play an important role in man's efforts to combat disease and other economically detrimental effects of microorganisms. Traditionally, antibiotics have been identified by screening microorganisms, especially those found naturally in soil, for their ability to produce an antimicrobial substance. In some cases, the gene or genes responsible for antibiotic synthesis have then been identified and cloned into producer organisms which produce the antibiotic in an unregulated manner for commercial applications. However, it has been estimated that less than 1% of the microorganisms present in soil are culturable. Torsvik et al., Appl. Environ. Microbiol. 56: 782-787 (1990). Thus, much of the genetic diversity potentially available in soil microorganisms is unavailable through traditional techniques.
As pathogenic microorganisms become increasingly resistant to known antibiotics, it would, however, be highly desirable to be able to access the reservoir of genetic diversity found in soil, and to facilitate the exploration of new species of antibiotics which may be made by the vast numbers of unculturable organisms found there. It would further be desirable to have access to novel biosynthetic enzymes and the genes encoding such enzymes, which could be used in recombinant organisms for antibiotic production or for in vitro enzymatic synthesis of desirable compounds. Thus, it is an object of the present invention to provide a method and compositions for isolating DNA and DNA fragments encoding enzymes relevant to the production of pharmaceutically active molecules such as antibiotic biosynthesis enzymes.